Title

Authors

ORCID IDs

First Advisor

Mark Pegg

Date of this Version

7-2017

Citation

Turner, Dylan R. "Trophic Dynamics of Flathead Catfish in the Missouri River Bordering Nebraska." (2017). M.S. thesis, University of Nebraska.

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Mark A. Pegg. Lincoln, Nebraska: July 2017

Copyright (c) 2017 Dylan R. Turner

Abstract

Understanding the trophic dynamics of large, riverine ecosystems is complex and requires knowledge from several inputs and outputs of the ecosystem. Most riverine ecosystems have been altered in some way whether through damming, channelizing, or diverting water. The Missouri River is not immune to these anthropogenic alterations. The river has dams throughout its middle portion and is channelized from Sioux City, Iowa to its confluence with the Mississippi River. Flathead Catfish pylodictus olivarius are one of the most ecologically harmful introduced species but little research has looked at the influence native populations of Flathead Catfish have on native prey populations where river modification has occurred. I collected Flathead Catfish diet samples and analyzed potential and realized prey caloric content to answer questions on how this abundant, apex predator influences prey populations within their native range. Flathead Catfish had similar diets among three distinct seasons (spring, summer, fall), selected for three fish species (Common Carp, Flathead Catfish, and Shovelnose Sturgeon) and two macroinvertebrate taxa (Ephemeroptera and Plecoptera), and consumed prey resources in similar quantities to introduced populations. The caloric values for prey items varied but selected species did not have highest nor lowest values. Using our diet indices and consumption rates, I estimated that Flathead Catfish consumed on average 175.3 ± 2.1 kcals (dry weight) per individual per day, equivalent to around 220.9 kg of biomass consumed by the entire sample population daily. This research will help researchers better understand the trophic dynamics within the Missouri River ecosystem.